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/*
* Copyright 2011, Blender Foundation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "stdosl.h"
shader node_brightness(
color ColorIn = color(0.8, 0.8, 0.8),
float Brightness = 0.0,
float Contrast = 0.0,
output color ColorOut = color(0.8, 0.8, 0.8))
{
float delta = Contrast * (1.0 / 200.0);
float a = 1.0 - delta * 2.0;
float b;
/* input value is a percentage */
float bright_factor = Brightness / 100.0;
/*
* The algorithm is by Werner D. Streidt
* (http://visca.com/ffactory/archives/5-99/msg00021.html)
* Extracted of OpenCV demhist.c
*/
if (Contrast > 0.0) {
a = (a < 0.0 ? 1.0 / a : 0.0);
b = a * (bright_factor - delta);
}
else {
delta *= -1.0;
b = a * (bright_factor + delta);
}
ColorOut = a * ColorIn + b;
}
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